And that important part lead to a dead end. Now the formula for the LEGO Movie has been tainted, not just by this character, but a good amount of it was. They couldn't do a sequel without it being absolutely terrible.
Given that it made half the money the last one did, maybe LEGO will take that into mind.
There ever being a good sequel. Her existing is not a problem, her continuing to exist after the train wreck of a plot is the problem.